The following is based on Korean Patent Application No. 00-5648 filed Feb. 7, 2000, herein incorporated by reference.
1. Field of the Invention
The present invention relates to a secondary electron amplification structure employing carbon nanotube and a plasma display panel and back light using the same.
2. Description of the Related Art
Display devices can be largely classified into either Braun tubes or flat panel display devices. A flat panel display device is thin and convenient to carry compared to a Braun tube. Moreover, a flat panel display device consumes less power than a Braun tube. For this reason, a new market for a flat panel display devices compensating for these drawbacks of Braun tubes has been made.
Representative flat panel display devices are liquid crystal displays (LCDs), plasma display panels (PDPs) and field emission displays (FED). PDPs are favorable for large screen displays so that they can compensate for the drawbacks of LCDs. Photomultipliers such as photomultiplier tubes (PMTs) and microchannel plates (MCPs) compensate for the drawbacks of these display devices by improving luminance.
FIG. 1 is a perspective view of a conventional surface discharge type triode plasma display panel (PDP) widely used at present. FIGS. 2A and 2B are vertical sectional views of the surface discharge type triode PDP taken widthwise and lengthwise. As shown in the drawings, a surface discharge type triode PDP includes a front glass substrate 20 and a rear glass substrate 10 which face each other with a predetermined gap therebetween. Partition walls 13 are formed between the gap to partition the space and construct cells having discharge spaces 21 corresponding to pixels. Each of the discharge cells for provoking discharge includes an address electrode 11, a scanning electrode 14 and a common electrode 15. The scanning electrode 14 and the common electrode 15 are disposed on the same plane and in a plane parallel to and axially orthogonal to the address electrode 11, thereby provoking surface discharge and displaying an image when the electrodes are appropriately charged. Reference numeral 12 indicates a dielectric layer, reference numeral 17 indicates a luminescent material, reference numeral 16 indicates a bus electrode, reference numeral 18 indicates a dielectric layer and reference numeral 19 indicates a MgO protection layer.
As described above, the PDP provided with plasma discharge spaces formed by partition walls mounted on a substrate displays an image by provoking discharge. The partition wall 13 is formed to have a uniform pattern using a printing method. The partition wall 13 allows a discharge in a cell to be discriminated from a discharge of an adjacent cell.
The MgO protection layer 19 enhances the efficiency of the discharge cell by emitting secondary electrons in the discharge cell to thereby decrease discharge voltage applied between electrodes. Consequently, the MgO protection layer 19 serves to protect the electrodes within the PDP.
Since materials conventionally used for PDPs, FEDs and photomultipliers have a low secondary electron emission coefficient, they have a low electron amplification factor. This increases voltage and weakens luminance. A PDP using discharge has discharge cells having discharge spaces for facilitating discharge. A MgO layer is formed in the space within each discharge cell as a protection layer. The MgO layer is usually made by forming a thin film using a sputtering method and an electron beam evaporation method. However, deposition of only single material, MgO, has a limitation in achieving a sufficient secondary electron emission effect within a plasma discharge space. In addition, it is desirable for the secondary electron emission to be enhanced in FEDs and photomultipliers such as PMTs and MCPs.
To solve the above problems, it is an object of the present invention to provide a secondary electron amplification structure for maximizing secondary electron emission using a carbon nanotube while maximally sustaining the advantage of a MgO layer emitting secondary electrons.
It is another object of the present invention to provide a plasma display panel and a liquid display panel back light, which employ the secondary electron amplification structure capable of lowering a driving voltage and improving luminance by maximizing secondary electron emission.
Accordingly, to achieve the above objects, the present invention provides a secondary electron amplification structure including a carbon nanotube layer, and a MgO layer stacked on the carbon nanotube.
It is preferable that, instead of the MgO layer, a layer formed of MgF2, CaF2, LiF, Al2O3, ZnO, CaO, SrO, SiO2 or La2O3 is used, and the carbon nanotube layer is deposited on an electrode formed of at least one metal among Cs, W, Mo, Ta, Fe and Cu.
To achieve the above objects, the present invention also provides a plasma display panel including front and rear substrates disposed to face each other with a predetermined gap therebetween, electrodes formed between the facing front and rear substrates, the electrodes crossing one another in a striped pattern, partition walls formed between electrodes on the rear substrate parallel to the electrodes, the partition walls allowing the predetermined gap between the front and rear substrates to be sustained, the partition walls forming discharge cells, and luminance materials deposited on the sides of the partition walls and on the electrodes on the rear substrate. The plasma display panel employing a secondary electron amplification structure includes a carbon nanotube layer formed on the electrodes on the front substrate, and a MgO layer stacked on the carbon nanotube layer.
Instead of the MgO layer, a layer formed of MgF2, CaF2, LiF, Al2O3, ZnO, CaO, SrO, SiO2 or La2O3 may be used. The electrodes may be formed of at least one metal among Cs, W, Mo, Ta, Fe and Cu. The plasma display panel also includes a carbon nanotube between each luminescent material and each electrode on the rear substrate and/or a carbon nanotube layer on each partition wall between each luminescent material and the MgO layer.
To achieve the above objects, the present invention also provides a surface discharge type triode plasma display panel including front and rear substrates disposed to face each other with a predetermined gap therebetween, address electrodes formed on the rear substrate in a striped pattern, partition walls formed between the address electrodes on the rear substrate parallel to the address electrodes, the partition walls allowing the predetermined gap between the front and rear substrates to be sustained, the partition walls forming discharge cells, luminance materials deposited on the sides of the partition walls and on the address electrodes, scanning electrodes and common electrodes formed parallel to each other on the front substrate with a predetermined gap therebetween, the scanning and common electrodes crossing the address electrodes in a striped pattern, and a dielectric layer deposited on the front substrate such that the scanning and common electrodes are covered with the dielectric layer. The plasma display panel employing a secondary electron amplification structure includes a carbon nanotube layer formed on the dielectric layer, and a MgO layer stacked on the carbon nanotube layer.
Instead of the MgO layer, a layer formed of MgF2, CaF2, LiF, Al2O3, ZnO, CaO, SrO, SiO2 or La2O3 may be used. The electrodes may be formed of at least one metal among Cs, W, Mo, Ta, Fe and Cu. The surface discharge type triode plasma display panel also includes a carbon nanotube layer between each luminescent material and each electrode on the rear substrate and/ or a carbon nanotube layer on each partition wall between each luminescent material and the MgO layer.
To achieve the above objects, the present invention also provides a back light including front and rear substrates disposed to face each other with a predetermined gap therebetween to form a discharge space, a first electrode formed on the surface of the front substrate in the discharge space, a luminescent material layer formed on the first electrode, a second electrode and a third electrode formed parallel to each other on the rear substrate in the discharge space with a predetermined gap therebetween, the second and third electrodes sustaining discharge, a dielectric layer deposited on the rear substrate such that the second and third electrodes are covered with the dielectric layer, and partition walls for allowing the predetermined gap between the front and rear substrates to be sustained and sealing the discharge space tightly. The back light employing a secondary electron amplification structure includes a carbon nanotube formed on the dielectric layer, and a MgO layer stacked on the carbon nanotube layer.
Instead of the MgO layer, a layer formed of MgF2, CaF2, LiF, Al2O3, ZnO, CaO, SrO, SiO2 or La2O3 may be used. The second and third electrodes may be formed of at least one metal among Cs, W, Mo, Ta, Fe and Cu. The back light also includes a carbon nanotube layer between the luminescent material layer and the first electrode.